Scanning Transmission Electron Microscopy and Related Techniques for Research on Actinide and Radionuclide Nanomaterials

Abstract

Due to their high solubility and ability to form crystals of good quality, uranyl selenates can be considered as a kind of model systems for studies of at least some of the nanoscale processes occurring in actinide-bearing natural and technological systems. Uranyl selenates display an exceptional structural diversity that can be studied using topological and computational methods such as graph theory and cellular automata. This allows to suggest models of nanoscale self-assembly that occurs during crystallization of uranyl selenates, which is most likely based upon successive condensation of cyclic tetramers. The most interesting feature is the ability of uranyl selenates to form nanotubular structures of at least two types. In organically templated systems, the formation of nanoscale composites and molecular control upon structural architecture is governed by the delicate balance of hydrophilic/hydrophobic interactions of organic molecules that results in the formation of nanoscale supramolecular aggregates and the interactions of these aggregates with inorganic complexes.